Production of cyclic mono-sulfones



Patented May 20, 1947 PRODUCTION OF CYCLIC MONO-SULFONES Rupert C. Morris and Harry ale V. Finch,

Berkeley, Calif., assignors to Shell Development Company, San Francisco, Calif, a corporation of Delaware No Drawing. Application June 15, 1943, Serial No.4905931 This invention relates to the production of cyclic mono-sulfones, and moreparticularly pertains to a novel process for the economical production of highyields of 3-sulfo1ene and of its substituted'derivatives'by thefinteraction of sulfur dioxide with poly-oleiinic organic compounds containing at least two olefinic linkages in conjugated relationship.

It is well known that cyclic mono-sulfones are valuable compounds which may be used as such in various organic syntheses, for example as intermediates for the manufacture of organic dyestuff and textile assistants. Also, at least some of the cyclic sulfones, such as 2,4dimethyl-4-- sulfolene, are suitable as solvents for the selective solvent extraction of various organic mixtures. Furthermore, it is known that cyclic mono-sul- [ones may be readily decomposed into sulfur, diox; ide and the poly-olefin employed in the original production of the sulfone, such decomposition being usually eii'ected by simple heating of the cyclic mono-sulfone or sulfones, preferably at a subatmospheric pressure. This characteristic of cyclic mono-sulfones affords a ready method for the separation of poly-olefins from the corresponding more saturated hydrocarbons. For instance, it is known that hydrocarbon fractions,

6 Claims. (Cl. 260-329) pyrolysis (which fraction may boil between about 55 C. andabout 80 C.) will predominate in various olefins having six carbon atoms per molecule and may contain, besides the different hexenes (i. e., straight chain or branched chain monoolefins having six carbon atoms per molecule), various hexadienes and particularly the branched-chain hxadienes, such as Z-methyl pentadiene-1,3 and 4-methy1 pentadiene-LB. These branched-chain dienes are very valuable products, being highly suitable as an ingredient in the manufacture of synthetic rubber. Also, the cyclic monosulfones formed by the interaction of these methyl pentadienes with sulfur dioxide,

even when they boil within a relatively narrow range, consist of a number of different hydrocarbons having different structures, possessing different properties and characteristics, and suitable for different uses, particularly due to the difference in the degree of saturation of the various constituents of such hydrocarbon fractions. As an example, when a hydrocarbon fraction formed by the pyrolysis of hydrocarbons of the type of naphtha. kerosene, stove oil or the like, is fractionally distilled to recover separately a fraction boiling between about 25 C. and about 50 C. to 55 C.. this narrow boiling fraction will predominate in various olefins having five carbon atoms per molecule. Besides the different straight as hydrogen halides.

when hydrogenated are highly suitable as selec tive solvents. I

It has been previously proposed to'separate cyclic dioleflns from narrow boiling'olefin-containing or olefin-predominating hydrocarbon fractions by contacting such fractions, at elevated temperatures and pressures, with sulfur dioxide to form the sulfones of .the acyclic dioleflns. The chief dimculty of this method lies in the fact that instead of forming cyclic mono-olefins which upon heating readily decompose to yield substantially quantitative amounts of the diolefins, a reaction between the acyclic diolefins and sulfur dioxide tends toward the formation of insoluble, amorphous products which do not readily yield the diolefins when subjected to ordinary processes of decomposition. The amorphous compounds are poly-sulfones, while the compounds which may be readilydecomposed into the starting materials, namely sulfur dioxide and the polyoleflns, are the cyclic mono-sulfones, i.e. mono.. meric poly-olefin sulfones. 1

Although it has been previously proposed to avoid the formation of the amorphous poly-sulfones during the interaction between poly-olefins and sulfur dioxide, all of the known processes of inhibiting such'poly-sulfone formation are attended by certain difliculties which render their use uneconomical or undesirable. For instance, it has been previously proposed to inhibit the formation of the amorphous sulfones by the use of certain halogen-containing substances such The use of such acids is undesirable because of their tendency to react with the olefins present in the hydrocarbon mixtures subjected tothe action of sulfur dioxide. Also, the presence of halogen compounds makes the subsequent hydrogenation of the sulfolenes impossible. at least as far as the use of nickel hydrogenation catalysts is concerned. It has also been proposed to inhibit the formation of amorphous poly-sulfones by avoiding the presence of a large excess of the sulfur dioxide in the reaction zone. Inacoordance with this proc-, es the poly-olefins or poly olefln-containing hydrocarbon fractions ar treated at suitable temperatures and pressures, with relatively small amounts of sulfur dioxide, e. g.'less than half theamount necessary to react with the dioleflns present in the reaction zone. It is obvious that such a treatment, if effected ina'batchprocess, does not result in the separation of all o'f'the poly-olefins. If eifected in a .continuous or intermittent system, such use of relatively small amounts of sulfur dioxide necessitates the repeated recycling of the hydrocarbon fractions into the reaction zone, thus increasing the cost of operation and requiring relatively long periods of time for the effecting of the 'desired' conversion of the poly-oleflns tothe corresponding cyclic'mono-oleflns. The term-.sulfolene" as used in thisspeciflcation is understood to mean the chemical compound thiocyclopentene- 1,1-dioxide and the term a sulfolene is un- Q derstood to mean a substituted derivative thereof wherein one or more of the hydrogen atoms are substituted by various radicals or elements.

It is an objectof the present invention to avoid the above and other defects and to provide an economical process for the efficient conversion of unsaturated organic compounds, containing two or more double linkages, and particularly those containing at least two oleflnic linkages in conjugated position, to the corresponding cyclic mono-sulfones. It is another object of the invention to provide a process whereby cyclic monosulfones may be readily and rapldly'formed in U high yields while avoiding or at least greatly inhibiting the formation of the undesirable amorphous poly-sulfones which, as stated, are usually formed whenv poly-unsaturated organic com- 40 pounds, e. g. poly-oleflns, are reacted with sulfur dioxide under conditions favoring. the formation offsulfones.

In some cases, e. g., when 2-methylpentadiene- 1,3 and/or 4-methy1 pentadiene-1,3, or hydrocarbon fractions containing these or other like diolefins, are reacted in the known manner with sulfur dioxide, it is found that there occurs a polymerization of these dioleflns instead of a formation of the desired cyclic mono-sulfones or even of the undesirable poly-sulfones. It is therefore a still further object of the'present invention to provide a process wherein the polymerization of the diolefins is inhibited, and wherein the interaction between such poly-olefins and the sulfur dioxide resultsina substantially quantitative conversion of the acyclic poly-olefins to the corresponding cyclic mono-sulfones.

It has now been discovered that the above and other objects may be attained by the use of polyunsaturated organic compounds, e. g. poly-olefins or poly-olefin-containing hydrocarbon fractions which are substantially free from peroxides. Broadly stated, it has been discovered that it is possible to effect a rapid reaction between sulfur 05 dioxide and poly-oleflns, particularly those containing at least two oleflnic linkages in conjugated position, to produce high yields of the desired cyclic mono-sulfones and at the same time inhibit side reaction, e. g. polymerization and/or formation of the undesirable amorphous, difl'lcultly decomposable poly-sulfonea by employing polyolefins or poly-olefln-containing hydrocarbon fractions which are free or substantially free of peroxides and by using sulfur dioxide in amounts 75 4 greatly in excess of the amountnecessary to combine with all of the poly-olefins present" in the reaction zone. When the hydrocarbon fraction subjected to the action of sulfur dioxide in accordance with the process of the present invention is free or substantially free from peroxides, the use of large amounts of sulfur dioxide, i. e.-amounts greatly in excess of those a necessary to combine with the poly-oleflns, does not tend to form the undesirable amorphous polysulfones or cause the polymerization of the poly-. oleflns, but merely permits a more rapid reaction between the poly-olefins and the sulfur dioxide, and results in high and even substantially quantitative yields of the desirable mono-suifones.

Although the process of the present invention is applicable to the reaction of sulfur dioxide with various poly-unsaturated organic compounds, it is particularly suitable for the treatment of straight chain and/or branched chain unsaturated hydrocarbons containing at least two oleflnic linkages in coniugated position, i. e. compounds having the general structural formula in which the substituents R1 to Re inclusive are selected from the group consisting of the hydrogen atom and the alkyl, alkenyl, aryi, alkaryl, aralkyl, cyclo-alkyl and 'cyclo-alkenyl groups or radicals. As suitable aliphatic poly-oleflns which may be converted 'to the corresponding cyclic mono-sulfones in accordance with the process of the present invention, reference may be made to the dioleflns with conjugated double bonds such as butadiene-1,3, 2-methyl butadiene-1,3 (isoprene) pentadiene-1,3 (piperylene) 2,3-dlmethyl butadiene-1,3, 2,3-dieth'yl butadiene-1,3, 2,3-ditertiary-butyl butadiene-1,3, Z-tertIary-butyl butadiene-1,3, 1,2,3,4-tetramethyl butadiene-1,3, l,4-dimethyl-2,3-diethy1 butadiene-1,3 2-methyl pentadiene-lfi, 4-methyl pentadiene-1,3, Z-methyl hexadiene-l,3, 4-ethyl'hexadiene-L3, and the like, and their homologues and analogues. Compounds having more than two double bonds. particularly when these olefinic linkages are in con jugated relationship, are also suitable compounds which may be treated with sulfur dioxide in accordance with the process of the present invention. The straight chain poly-olefins of the class described above may also have cyclo-alkyl, cycloalkenyl, and/or aromatic radicals linked to carbon atoms of primary, second and/or tertiary character, examples of such compounds being cyclo-pentyl butadienes, cyclopentyl pentadienes, cyclohexyl butadienes, 2-phenyl butadiene-LB, 2,3-diphenyl butadiene-1,3, and the like and their homologues and analogues. Also, suitable substituted derivatives of the above and like polyolefins may be reacted with sulfur dioxide to form the desired mono-sulfones, examples of such substituted poly-oleflns being 2-chlorbutadiene-l,3, 2-methyl-3-chlorbutadiene-1,3, l-cyano butadiene-1,3, and the like. I

The invention may therefore be stated to reside in a process of producing cyclic sulfones by reacting substantially peroxide-free unsaturated organic compounds of the class defined above with sulfur dioxide employed in an amount greatly in excess of that necessary to react with the poly-oleflns or poly-olefinic compounds, this reaction being effected under the hereinbelow described operating conditions favoring the forto the action of light and/or air. tion or these organic peroxides from the unsataeaaese mation or the suliones. The use of the large amounts or suli'ur dioxide permits a rapid reaction, while the absence tion mixture inhibits or at least greatly reduces the tendency towards formation or the undesirable amorphous polysulfones and/or. 01' hydrocarbon polymers, so that the execution of the process results in a rapid and economicalproduction or high yields 01' the desired cyclic monosulfones. 1

It is known that unsaturated organic compounds, and particularly those containing a plurality of conjugated double bonds, readily tend to form organic peroxides upon standing, especially when such unsaturated compounds are exposed The separaurated compounds may be effected by a plurality of well-known processes. It has been found that a particularly suitable method for the separation and recovery of substantially peroxide-free unsaturated organic compounds from unsaturated compounds which have been exposed to the action of air and/or light, which unsaturated compounds therefore. contain greater or lesser concentrations oi the organic peroxides, may be effected by subjecting the peroxide-containing mixtures to a distillation in the presence of a strong base or of a basic-acting compound, the use of the latter during such distillation preventing dangerous explosions when peroxide-containin mixtures are subjected to ordinary distillations in the absence of such basic compound. Strong bases such as alkali metal hydroxides of the type of sodium hydroxide may be employed either as such or in the form of their aqueous or alcoholic solutions. The amount of the basic or basic-acting material to be added to a given unsaturated fraction to be subjected to distillation will vary depending on the specific basic or basic-acting compound employed, the particular unsaturated compound to be distilled, and the amount or concentration or the organic peroxides in the fraction to be purifled. Generally, it has been found that aqueous sodium hydroxide solutions may be used in amounts ranging from about 5% to about 20% by volume of the unsaturated organic fraction to be treated. However, greater or lesser amounts of such basic or basic-acting compound may also be employed. The mixtures of the unsaturated compound to be treated and of the basic material may be subjected to flash distillation; the temperature being that at which the peroxidefree unsaturated compound or compounds will be vaporized so that they may be recovered as an overhead fraction. When relatively high boiling unsaturated compounds are to be thus purified, it is preferred pheric pressures to prevent polymerization and/or other undesirable side reactions. Since the unsaturated compounds, erg. olefins, and' particularly the fractions which contain relatively high percentages 01' Doly-olefins, are, as stated above, quite reactive and will tend to form organic peroxides even by a mere contact with air and/orlight even at ordinary temperatures and pressures, it is essential to prevent any further formation of the organic peroxides in the interim between the purification step and the time when the peroxide-free fraction is reacted with sulfur dioxide under conditions favorable to the formation of the cyclic mono-sulfones by the interaction of the sulfur dioxide with the polyolefins or poly-unsaturated organic compounds which frequently occurto employ subatmos peroxides in the reacdition products, i.

present therein. This may ing the peroxide-free fractions with the dioxide substantially immediately after the removal oi the peroxides therefrom, by the addition or variou inhibitors such'as droquinone,

or the like, to the purified fraction, by storage sired mono-sulfones during the interaction between the sulfur dioxide unsaturated compound.

Although generally speaking the mol ratio of the sulfur dioxide to the poly-oleflns may vary within relatively wide limits,.it has been pointed out above that high yields of the desired monomeric cyclic sulfones are obtainable when the sulfur dioxide is employed in amounts greatly in excess 01' those necessary for the conversion of all of the poly-oleflns into the corresponding cyclic mono-suliones. As long as the poly-olefinic organic compounds are free or substantially free from organic peroxides, an increase in the mol ratio'of the sulfur dioxide to the poly-olefinic organic compounds, other conditions being maintained equal, will increase the yield of the cyclic unsaturated mono-sullones' obtained when such mixtures of the sulfur dioxide and of the polyolefinic organic compound or compounds are sub- Jected to temperature and pressure conditions favoring the interaction between these reactants. For example, other conditions being maintained equal, by increasing the mol ratio of Islllftll' dioxide to isoprene from about 2:1 to about 4:1 it is possible to raise the yield of the isoprene sulione (3,-methyl-3-sulfolen) from about 78% to 89.5%. This increase in the yield of the monosulfones is eilected in accordance with the process of the present invention without the use of any and the peroxide-free catalysts and/or 'restraining agents, the sole requirement being that the poly olefin containing hydrocarbon fraction must be free from organic peroxides. As pointed out above,'this discovery is contrary to well-accepted opinions to the eflect that the use of sulfur dioxide in excess of the amount necessary-to combine with the acyclic dioleflns tends to form insoluble, amorphous ade'. poly-suifones. As stated, and contrary to the above mentioned previous opinions, the use of sulfur dioxide in amounts in excess 01' those necessary to combine with all of the poly-oleflnic organic compounds present in the reaction mixture will increase the yield of the cyclic mono-sulfones without any substantial formation of the insoluble, amorphous poly-sulfones and without any substantial polymerization of the unsaturated hydrocarbons if the reactants .are free or substantially free from organic perratios, 76

oxides. It has been discovered that satisfactorily high yields of the desirable mono-sulf ones may be obtained when the reaction mixture contains sulbe eflected by atation, and the sulfur dioxide to form the unsatu'-- rated cyclic sulfones, i. e. sulfolene' andits' de; rivatives, is preferabiyfeffected while maintain ing the reactants in the liquid phase or at least under such conditions that the reactants are predominantly in the liquid state. Generally, the reaction temperature should be maintained in the neighborhood of 100 0., although somewhat higher or lower temperatures may also be employed. The optimum reaction temperature de-' pends at least in part upon the specific poly-oleiinic organic compoundtreated. when the operating temperature drops too low, the addition reaction, even in the case of those poly-oleflnic compounds which-have a relatively high reaction rate with respect to the desired addition reaction.

. f8 and these mono-sulfones may then be decom- P sed to liberate the sulfur dioxide and recover the poly-olennic compound which originally re-' acted with the sulfur dioxide to form the sulfolenes. This decomposition may be effected, for example, by heating the separated sulfolenes to a temperature sufilciently high to cause the decomposition thereof. LASB- general rule this heating should be effected under reduced pressures in order to inhibit or prevent the polymerization of the poly-oleflnic compounds thus liberated. However, with certain of the sulfolenes, it is possible to eifect their decomposition at atmospheric pressure. Obviously the decomposition temperature will vary depending on the specific sulfolene treated, as well as on the pressure employed. For

instance, when effected at or about atmospheric becomes so low as to render the process uneconomical. Also, the use of such low temperatures frequently increases the yield of the undesirable poly-sulfones. On the other hand, care should be taken to avoid the use of temperatures which are suillciently high to cause the decomposition of the formed mono-sulfones back to the starting reactants.

Although. the sulfone formation reaction may be effected at pressures which are only sufilcient .to maintain the reactantsin the liquid state at the operating temperature employed, higher pressures may also be used. Generally the reaction pressure is higher than that at which the reactants are introduced into the reaction vessel.

This is due to the fact thatit is usually preferable to effect the introduction of reactants into the reaction vessel or autoclave at or below ordinary temperatures in order to maintain the reactants in the liquid state during such introduction, whereas the reaction temperature, as stated, is in the neighborhood of about 100 C. The reaction pressures thus generated in the autoclave are between about 100 pounds per sq. in. and about 500 pounds per sq. in, or even higher, depending in part on the specific poly-olefinic compound or compounds treated. The residence time will vary depending on the specific polyolefinic organic compound or compoundswhich are reacted with sulfur'dioxide to eflect the formation of the desired corresponding unsaturated cyclic mono-sulfone or sulfones;

It was pointed out above that the monomeric sulfones find utility in various industries and may 1 be used either as-such, e. g. as solvents, or may be employed as intermediates in the manufacture of various other. chemical compounds, It was also brought'out above that the various sulfolenes, i.- e. unsaturated cyclic monomeric sulfones, may be readily decomposed to form mixtures comprising or consisting of sulfur dioxide and the starting unsaturated compound or compounds'by subjecting the sulfolene favor their decomposition. This permits the use of the sulfone-formation step for the separation to temperatures which of the poly-olefins from mixturescontaining them and other more saturated organiccompounds. In such a case, after the termination ofthe addition reaction between the-sulfur dioxide and the poly-olefinic organic. compounds, e. g.- poly-olefinic hydrocarbons containing two olefinic linkages in conjugated position, the sulfolenes may then be separated from the unreacted hydrocarbons, if any, and from the excess sulfur dioxide,

pressure, the decomposition of 2,4-dimethyl-3- sulfolene necessitates a temperature of between about 120 C. and about 130 C., while the use of a reduced pressure, e. g. of the order of about 50 mm. of mercury pressure, permits decomposition at temperatures of between C. and C. The separation of the obtained poly-olefin from the reaction product may be effected by any known means. For example, when the decomposition of the unsaturated cyclic sulfones, i. e. sulfolenes, is effected by distillation, the overhead gaseous fraction may be conveyed through scrubbers containing an alkaline solution, e. g. a 10% aqueous solution of sodium hydroxide, which removes the liberated sulfur dioxide, the remaining gaseous fraction comprising or consisting of the original poly-olefinic compounds which reacted with the sulfur dioxide to form the sulfolenes, or at least structural isomers of such poly-olefinic compounds. Another method of separating the sulfur dioxide from the diolefins comprises scrubblng the overhead gaseous mixture with a liquid hydrocarbon oil such as a high boiling naphtha, kerosene, or gas oil, which selectively dissolves the poly-oleflns. The latter may then be. separated from the solvent by any known means. This method of separation is described more fully in U. S. Patent No. 2,264,878.

, The invention is further illustrated by the following specific examples, it being understood that there is no intention of being limited by any details thereof, since many apparent variations may be made.

Example I were then introduced into an evacuated bomb re,-'

actor which was chilled by means of a solid carbon dioxide bath. Approximately 1.2 mols of liquid sulfur dioxide and about 0.9 mol of the above hydrocarbon fraction (which contained about 0.38 mol of butadiene-l,3) were thus introduced into the reactor. sulfur dioxide to the butadiene was therefore equal to about 3.14:1. The reactor was then closed and placed into boiling water so as to maintain the reaction within the reactor at about 97 C. The reaction was continued for about two hours, after which the unreacted gases were released. An analysis of the reaction products showed that approximately 86 mol per cent of the butadiene reacted to form sulfones. The

The mol ratio of the yield of the desirable cyclic mono-milfone, i. e. 3-sulfolene, was equal toabout 77.6 mol .per cent.

v -E:ramplell' A hydrocarbon fraction comprising butylenes' and buta'diene, but containing some organic per-1' oxides, was mixed with about by volume of an aqueous sodium hydroxide solution. the mix- 1 distillation to same temperatures and pressures as those employed in the previous example, thisreaction being continued for about 2 /2 hours. An analysis of the reaction products indicated that the total 1 yield of sulfones was equal to about 98.8 mol percent, and' that the yield of the undesirable polysulfones was less than 0.3%. I

A comparison of the results obtained in the above two examples clearly shows the advantages which are obtained by effecting the sulfone formation in accordance with the process of the present invention. Thus the removal of the peroxides from the treated hydrocarbon fraction greatly decreased the formation of the undesirable poly-sulfones. free hydrocarbons permitted the use of a higher sulfur dioxide to-diolefin mol ratio resulted inva reaction between the sulfur dioxide and substantially all of the diolefins present in the reaction zone, and at the same time substantially inhibited the production of the undesirable polylfones- Example III A hydrocarbon fraction boiling between 32 and 36 C. and produced by thermal cracking of the second cut straight run gasoline was employed. This fraction (which predominated in olefins having 5 carbon atoms per molecule) was found by analysis to contain approximately 47.5% by weightof isoprene together with some organic peroxides which were present in the fraction in spite of the fact that it contained hydroquinone. This peroxide-containing hydrocarbon fraction and sulfur dioxide were then separatelyliquefied and introduced into an evacuated bomb reactor. Approximately 1.11 mols of liquid sulfur dioxide and about 0.513 mol of the above hydrocarbon fraction (which contained approximately 0.268 mol of'isoprene) were thus introduced into the reactor. The mol ratio of the sulfur dioxide was therefore equal to 4.14:1. The reactor was then closed and heated to a temperature of'about 99 C. for a period of about three hours. An analysis of the reaction products showed that about" 61% of the isomeric reacted to produce predominantly poly-sulfones.

Example IV a A hydrocarbon fraction predominating in olefins having 5 carbon atoms per molecule and containing about 44.3 m remainder being mono-olefins having 5 carbon atoms per molecule) was first distilledwith a strong base to obtain an overhead hydrocarbon distillate which is free from organic peroxides. This peroxide-free hydrocarbon fraction was y then liquefied an introduced into an evacuated In fact the use of peroxide- I was found to contain about of butadiene-L3. This byher as that described in Example III, the reaction period being equal to about 0.5 hour. An analysis of the reaction the isoprene reacted with the sulfur dioxide to produce substantially only 3-methyl-3sul folene (isoprene mono-sulfone). the reaction products being substantially free from any poly-sulfones.

A comparison of the results of Examples III and IV clearly shows the advantages of effecting the sulfone formation in accordance with the process of the present invention, the use of the peroxide-free hydrocarbon fractions permitting faster rates of reaction, greater conversions,

greater yields of desired mono-sulfone and substantial inhibition of the formation of by-products, e. g. undesirable poly-sulfones.

Example V A hydrocarbonfraction boiling between 41 C. and 44 C. and produced by straight distillation of the product formed by cracking second out straight run gasoline was employed. This fraction was first treated in the manner described in the previous example to remove any organic peroxides present therein. The overhead condensed distillate contained about 42.8 weight per the distillate cent piperylene. The formation of the sulfone was efiected according tothe process described in the above examples, the sulfur dioxide being used in a mol ratio of 4:1 and the reaction period being about two hour After removal of the unreacted products, it was found that approximately 96.3% of the piperylene originally present in the reactor combined with the sulfur dioxide to produce 2-methyl-3-sulfolene. Substantially no poly-sulfone was formed.

Example VI A methyl'pentadiene fraction, which was stored Q in a drum and which, was found to contain or- Example VII pentadiene fraction obtained from same source as that used in the preceding example was first flash distilled in the presence of a- 10% aqueous sodium hydroxide solution, the (which was thus free from peroxides) being then substantially immediately mixed with liquid sulfur dioxide and the mixture then treated in the same manner and under the same conditions as those described in Example VI. An analysis of the reaction product showed that the conversion to 2',4-di:nethyl-3-sulfolene was equal to about 80.8%, as based on the charged methyl A methyl pentadienes, and that only about 1.5% of these products showed that 99.5% of obtainable 7 As noted above, the presence of organic peroxides under the reaction conditions tends to form difllcultly decomposable poly-sulfones and/or the polymerization of the dioleflns employed. The mere addition of inhibitors of the type of DY.

rogallol is insumcient since they merely inhibit further formation of the peroxides and do not decompose those already present in the hydro carbons or hydrocarbon mixtures treated. Therefore, in order to produce high yields of the desirable mono-sulfones, it is necessary to destroy these peroxides, for example by the aforementioned distillation in the presence of a strong base, or otherwise destroy and remove the organic peroxides from the hydrocarbon fraction i 12 time sufllcient to' eiiect an addition reaction be.- tween the sulfur dioxide and the isoprene, and

' separating 3-methyl-3-suli'o1ene thus formed from the reaction mixture.

3. In a process for the production of high yields of 2-methyl-3-sulfolene while inhibiting the formation of poly-sulfones, the steps of mixing a peroxide-containing hydrocarbon fraction predominating in oleflns having five carbon atoms per. molecule and containing piperylene, with an aqueous sodium hydroxide solution, subjecting the mixture to a distillation to obtainsaid hydrocarbon; fraction in a substantiallyperoxidefree state, mixing said peroxide-free hydrocarto be subjected to the action of sulfur dioxide under temperature and pressure conditions which favor the formation of the corresponding cyclic sulfones.

This application is a continuation-impart of the co-pending application, Serial No. 404,084, filed July 25, 1941.

We claim as our invention:

1. In a process for the production of 2,4-dimethyl-3-sulfolene while inhibiting undesirable side reactions, the steps of mixing a hydrocarbon fraction boiling between about 55 C. and about 80 C., predominating in unsaturated hydrocarbons having six carbon atoms per molecule and containing 2-methy1 pentadiene-1,3 and 4-methyl pentadiene-1,3. which hydrocarbon fraction also contains organic peroxides, with an aqueous sodium hydroxide solution employed in an amount equal to about 10% by volume of the hydrocarbon fraction treated, subjecting this mixture to a distillation to obtain the hydrocarbon fraction bon fraction with liquid sulfur dioxide employed- 1 in an amount equal to about, 4 mols of sulfur d1- oxide per mol of the piperylene present in the hydrocarbon fraction treated, subjecting said mixture to a temperature in the neighborhood of about 100 0., at a superatmospheric pressure suflicient to maintain thereactants in the liquid state, and for a period of time sufllcient to effect an addition reaction between the sulfur dioxide and the piperylene, and separating 2-methyl-3- sulfolenethus formed from the reaction mixture. 4. In a process for the production of 2,4-dimethyl-3-sulfolene while inhibiting undesirable side reactions, the steps of mixing a hydrocarbon fraction containing 2-methylpentadiene-1,3, 4- m'ethylpentadiene-IB and organic peroxides, with an'aqueous solution of a basic-acting compound, subjecting this mixture to a distillation to obtain the hydrocarbon fraction in asubstantially peroxide-freestate. mixing said peroxidefree hydrocarbon fraction with liquid sulfur dioxide employed in an amount between about 2 mols and about 10 mols of sulfur dioxide per mol of the methyl pentadien'es present in the peroxa period of time suflicient to 'eflect an addition in a substantially peroxide-free state, mixing said peroxide-free hydrocarbon fraction with liquid sulfur dioxide employed in an amount equal to about 4 mols of sulfur dioxide per mol of the methylpentadienes present'in the hydrocarbon fraction treated, subjecting said mixture to a temperature in the neighborhood of about 100 C., at a superatmospherlc pressure sufllcient to maintain the reactants in the liquid state, and for a period of time suiiicient to effect an addition reaction between the sulfur dioxide and the methy1pentadienes, and separating the 2,4-dimethyl-3-sulfolene thus formed from the reaction mixture. 4

2. In a process for the production ofhigh yields of 3-methyl-3-sulfolene while inhibiting the formation of poly-sulfones, the steps of mixing a peroxide-containing hydrocarbon fraction predominating in oleiins having flve carbon atoms per molecule and containing isoprene with an aqueous sodium hydroxide solution, subjecting the mixture to a distillation to obtain the isoprene-containing hydrocarbon fraction in a substantially peroxide free state, mixing said peroxide-free fraction with liquid sulfur dioxide employed in an amount equal to'about 4 mols oi the sulfur dioxide per mol of the isoprene present in the hydrocarbon fractiontreated, subjecting said mixture to an elevated temperature in the neighborhood of 100? C.. at a superatmospheric pressure suiiicient to maintain the re-" reaction between the sulfur dioxide and the methyl pentadienes.

5. In a process for the production of high yields of cyclic monosulfones while inhibiting undesirable side reactions, the steps of subjecting 2-methylpentadiene-1,3 containing organic peroxides to a distillation in the presence of a basicacting compound, 'thereby obtaining the pentadiene in a substantially peroxide-free state, mix. ing said. substantially peroxide-free 2-methylpentadiene-1,3 with liquid sulfur dioxide employed in an amount between about 2 mols and about 10 mols of the sulfur-dioxide per mol of the methyl pentadiene, subjecting said mixture to an elevated temperature in the neighborhood of about 100 C. ata superatmospheric pressure sufficient to maintain the reactants in the liquid state and for a period of time suflicient to eflect an addition reaction between the sulfur dioxide and the methyl-pentadiene, and separating the 2,4-dimethyl-3-sulfolene thus formed from' the reaction mixture.

6. In a process for the production of monomeric cyclic sulfones while inhibiting undesirable side reactions of 'the type of polymerization and I formation of polysulfones, the steps of subjecting peroxides, to a distillation in the presence of a basic-acting compound to obtain said unsatuactants in the liquid state, and for 'a period of g5 rated hydrocarbon in a substantially peroxide.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,993,881 Perkins Mar. 5, 1935 5 2,076,524 Behrens Aug. 13, 1937 2,356,840 .Frey et al. Aug. 29,1944

. FOREIGN PATENTS Number Countryv Date 506,839 Germany ...a 1930 OTHER. REFERENCES Berichte, 683, pages 455-71 (1935).

Nash, "Principles of Motor Fuel Preparation and Application, vol. 11, pages 622-3 (1935), John WileyJzSons. 

